1. Field of the Invention
The present invention relates to high-speed photography using a high-speed camera, and especially relates to a technique for improving recording performance and enhancing user convenience at the time of playback.
2. Related Art
In recent years, data amounts of moving images have become larger to meet demand for higher picture quality. Particularly in the case of high-speed photography, a large amount of data needs to be recorded because of a high frame rate.
In view of this, techniques for reducing data amounts of moving images have been developed in consideration of processes such as recording the moving images onto recording media.
One of these techniques is a compression coding technique such as MPEG (Motion Picture Experts Group). This technique is devised to record one screen of data constituting a moving image, in a reduced data amount.
Also, a technique of reducing a size of a screen to be recorded so as to make a data amount smaller has been developed, too.
One example is a technique relating to a surveillance camera system that can reduce an amount of image accumulated when an abnormal condition is detected (see Patent Document 1).
This technique sets, within a screen for photographing a surveillance area (e.g. a screen 20 in FIG. 16), an area (e.g. an area A to an area D in FIG. 16) smaller than the screen in advance and, when a movement is detected in that area, records only the area in which the movement is detected. This will be explained in more detail later, with reference to FIG. 17.
According to this technique, by recording image data of a part that includes a movement, an amount of data can be reduced while realizing a function as a surveillance camera.    Patent Document 1: Japanese Patent Application Publication No. 2005-266373.